The present application is directed to an apparatus and method for attaching a wheel to an axle.
Many methods of attaching a wheel to an axle are known in the art. A wheel attachment must both secure the wheel to the axle and transfer torque and power efficiently from the axle to the wheel.
A common method employs a plurality of lug studs circumferentially spaced around the rotational axis of the axle. The lug studs are supported by a flange attached to the axle. The wheel is mounted on these lug studs through holes in the wheel that allow the studs to pass through the wheel. Lug nuts are screwed onto the lug studs, forcing the wheel against the flange as the lug nuts are tightened. The lug nuts retain the wheel on the axle and the torque and power of the axle are transferred to the wheel via the lug studs. The plurality of lug studs provides redundancy to the system since a loose lug nut will not cause the wheel to separate from the axle nor will it cause the wheel to slip relative to the rotation of the axle. The disadvantage of using more than one lug stud to secure the wheel to the axle is the added time required to attach or detach the wheel since more than one lug nut must be screwed or unscrewed from the lug studs. A second disadvantage is the additional cost associated with manufacturing the flange portion of the axle.
An improved approach for securing a wheel to an axle should: (a) maintain efficient torque and power transfer from the rotating axle to the wheel; (b) provide quick and easy attachment and detachment of the wheel from the axle; (c) provide redundancy for power transfer and (d) improve manufacturability by simplifying the design of the wheel and axle mating surfaces. Embodiments of the present invention address each of these needs.
In accordance with a preferred embodiment of the invention, a system is provided that has: (a) an axle having an indentation at a wheel-coupling end for a wheel hub; (b) a non-cylindrically-symmetrical lug stud, concentric with the axle, extending from the wheel-coupling end of the axle; (c) a wheel having a non-cylindrically-symmetrical clearance hole to admit the lug stud, the clearance hole at the center of the wheel; (d) a wheel hub, that is inserted into an indentation in the end of the axle; and (e) a fastener for attaching the wheel to the lug stud.
In accordance with a further embodiment of the invention, there is provided a method for securing a wheel to an axle. The method has the steps of: aligning the rotational axis of the wheel with the rotational axis of the axle; inserting the wheel hub into an indentation in an end of the axle; and fastening the wheel to the axle at a single point on the rotational axis of the wheel with a lug stud not possessing cylindrical-symmetry about the rotational axis of the axle.